Power consumption by electronic devices is an increasingly important factor in the design of electronic devices. From a global perspective, the energy consumption of electronic devices occupies a sizable percentage of total energy usage due to large corporate data centers and the ubiquity of personal computing devices. Environmental concerns thus motivate efforts to reduce the power consumed by electronic devices to help conserve the earth's resources. From an individual perspective, less power consumption translates to lower energy bills. Furthermore, many personal computing devices are portable and powered by batteries. The less energy that is consumed by a portable battery-powered electronic device, the longer the portable device can operate without recharging the battery. Lower energy consumption also enables the use of smaller batteries and the adoption of thinner form factors, which means electronic devices can be made more portable or versatile. Thus, the popularity of portable devices also motivates efforts to reduce the power consumption of electronic devices.
An electronic device consumes power if the device is coupled to a power source and is turned on. This is true for the entire electronic device, but it is also true for individual parts of the electronic device. Hence, power consumption can be reduced if parts of an electronic device are powered down, even while other parts remain powered up. Entire discrete components of an electronic device, such as a whole integrated circuit (IC) or a Wi-Fi radio, may be powered down. Alternatively, selected parts of a discrete component may likewise be powered down. For example, a distinct processing entity or a circuit block of an integrated circuit chip, such as a core thereof, may be selectively powered down for some period of time to reduce energy consumption.
A portion of an integrated circuit, such as a core, can therefore be powered down to reduce power usage and extend battery life. A core can be powered down by, for example, decoupling the core from a power source or otherwise causing the core to cease drawing an appreciable current level. Generally, if a core is not drawing current, the core is not consuming power. A strategy of turning off the current drawn by a core does reduce energy consumption. Unfortunately, this strategy also strains the operation of a power supply for the core.
In modern electronic devices, a power management integrated circuit (PMIC) generates and provides voltages for different loads, such as a core of an integrated circuit. The PMIC can be disposed on the same integrated circuit as the core being powered or a different integrated circuit. The PMIC is responsible for providing a stable, steady voltage to the core to enable the core to operate properly. During standard operation or as part of a power-conserving strategy, the core can draw a load current that fluctuates over time. Nevertheless, a voltage regulator of the PMIC is expected to be capable of maintaining a regulated output voltage level as the load current changes over time.
However, the ability of a voltage regulator to provide a stable output voltage is undermined if a load current of a load repetitively falls to a low current level and then climbs to a high current level. In response to such sudden repetitive changes in the load current, the voltage regulator provides an output voltage that exhibits a pronounced dip, such as by as much as 40% below a set point for the output voltage. This dip on the output voltage adversely affects the performance of the load. For example, the ability of a core to correctly perform processing operations is jeopardized, such as by slowing processing throughput while the voltage is being stabilized or even causing data to become corrupted. These concerns have hindered the rate at which cores can be powered down and therefore the ability of integrated circuits to conserve power by reducing the current flow to a circuit load.